Authors: Suhua Zhou
Addresses: Century College, Beijing University of Posts and Telecommunications, Beijing, 102613, China
Abstract: A simplified serial concatenated overlapped code division multiplexing (SC-OVCDM) system is proposed in this paper, in this scheme, inner overlapped code division multiplexing (OVCDM) code matrix is simplified into multiplexing matrix with constraint length 1, which can obtain two benefits. Firstly, system complexity has significant reduction. Moreover, the output constellation diagram distribution is close to the Gaussian distribution and can obtain better BER performance. Secondly, higher spectral efficiency greater than 4 bit/s/Hz can be achieved for its low complexity. Coded simplified SC-OVCDM system is studied at the first time, BCH (Bose, Ray-Chaudhuri and Hocquenghem) code correcting multiple errors is selected as error correcting code through error histogram analysis, simulations show shorten BCH codes which code rate is close to 1 can effectively eliminate high error floor and reduce loss of spectral efficiency. Proposed system performance needs joint optimisation of encoders, signal sets and multiplexing matrix. Novel multipexing matrices are given for systems that spectral efficiency equals to and greater than 4bit/s/Hz. Simulation results show the effectiveness of the optimal new scheme in AWGN channel.
Keywords: high spectral efficiency; serial concatenated overlapped CDM; code division multiplexing; SC-OVCDM; multiplexing matrix; symbol-level soft demodulation; BCH codes; simulation.
International Journal of Information and Communication Technology, 2016 Vol.9 No.3, pp.261 - 270
Received: 24 Mar 2014
Accepted: 29 Jun 2014
Published online: 13 Sep 2016 *